JPH04228055A - Puffing method for tobacco - Google Patents

Abstract

PURPOSE: To provide a new expanding method for tobacco with which the capacitance of tobacco to be charged is remarkably increased by practically selectively soaking only the small holes and porous surface of tobacco. CONSTITUTION: By mixing tobacco and cold carbon dioxide at a predetermined weight ratio, it is cooled to the predetermined temperature (a), this cooled tobacco is soaked in liquid carbon dioxide through treatment due to gas carbon dioxide to the predetermined pressure for the predetermined contact time under the condensation of this gas carbon dioxide (b), by rapidly lowering the pressure of this carbon dioxide, the liquid carbon dioxide condensed in the tobacco is transduced to solid carbon dioxide, at the same time, the gas carbon dioxide is formed (c) and the tobacco containing the solid carbon dioxide is expanded through hot gas treatment.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to tobacco expansion (expa
sion) method. wherein: (a) cooling the tobacco and cold carbon dioxide to a predetermined temperature by mixing them in a predetermined weight ratio; and (b) cooling the tobacco and cold carbon dioxide to a predetermined pressure by mixing the By treatment for a predetermined contact time under condensation of gaseous carbon dioxide,
impregnating the cooled tobacco with liquid carbon dioxide; (c) converting the liquid carbon dioxide that condenses in the tobacco into solid carbon dioxide by rapidly reducing the pressure of the carbon dioxide, while simultaneously forming gaseous carbon dioxide; , (d) subjecting the tobacco containing solid carbon dioxide to a hot gas treatment to expand it.

0002

BACKGROUND OF THE INVENTION Such a method is described in DE-A 34 45
752 (US-A 4 528 994). In all steps of the process, carbon dioxide is used, which is present in solid, liquid or gaseous form, depending on the requirements and reaction conditions. In the subsequent step of treating the tobacco with pressurized gaseous carbon dioxide, the first step is carried out with such a large amount of carbon dioxide that a mixture of solid carbon dioxide and tobacco is still present. The weight ratio of solid carbon dioxide to tobacco is
Preferably 96%/130%, especially 125%/128%
As a result, in addition to other desirable characteristics, a sufficiently high percentage increase in the filling capacity of the tobacco is obtained, inter alia, in the final expansion carried out by hot gas treatment. The known process is not only uneconomical because it requires very large amounts of carbon dioxide, in particular solid carbon dioxide, but also because of the large amount of carbon dioxide it requires a mixture of solid carbon dioxide and tobacco and gaseous carbon dioxide. During the subsequent processing, this excess solid carbon dioxide has the disadvantage of additionally forming excess liquid carbon dioxide. As a result, selective absorption of liquid carbon dioxide does not occur substantially only within the pores and on the porous surface of the tobacco. Additionally, there is a risk that excess carbon dioxide will cause the tobacco to freeze and form clumps.

A corresponding method for tobacco expansion is also described in DE-A 3445 753 (=US-A 463
0 619). This method is DE-A 3
The method differs from the method of 4 45 752 mainly in that, in the first step, the tobacco is cooled by treatment with liquid nitrogen, which obviously requires a relatively high pressure in the subsequent step of treatment with gaseous carbon dioxide. be. In the method, nitrogen is entrained throughout the cooling step.
), a gas mixture consisting of nitrogen and carbon dioxide is always formed in the next step. Economic capture and reuse of carbon dioxide is therefore not possible. Moreover, this known method also has the above-mentioned disadvantages of the method of DE-A 34 45 752, since it is not practical to selectively absorb liquid nitrogen only in the pores and on the porous surface of the tobacco. includes. It also includes excessive formation of solid carbon dioxide with subsequent excessive production of liquid carbon dioxide.

It is an object of the present invention to provide a new method for the expansion of tobacco, which, in particular due to its low carbon dioxide requirement and consumption and its reusability, is extremely economical and substantially reduces the amount of tobacco used. It becomes possible to selectively impregnate only the small pores and porous surfaces of the material, which at the same time leads to a particularly large increase in the filling capacity.

[0005]

[Means for solving the problem] In step (a), tobacco is
Expanding liquid carbon dioxide directly from a pressure tank into a closed system while forming an atomized mixture of cold gaseous carbon dioxide, carbon dioxide snow, and optionally liquid carbon dioxide, and simultaneously mixing with tobacco. by about -30°C to -100°C, preferably about -70°C.
This problem is solved by the method according to the invention, which is characterized by cooling between .degree. C. and -85.degree. Consequently, the method of the present invention comprises, in step (a), direct expansion of liquid carbon dioxide while simultaneously mixing the tobacco, by using the atomized cold mixture formed during said expansion. , the desired temperature is substantially between about -30°C and -100°C.
, preferably by cooling the tobacco to about -70 to -85°C. It is true that the use of liquid carbon dioxide in step (a) and therefore the kind of cooling treatment of the tobacco that is required ensures that in the next step liquid carbon dioxide is applied essentially only in the pores and on the porous surface of the tobacco. This would be the basis for the physical properties that the tobacco obtains in the first step, which selectively absorbs and are thus responsible, so to speak, for the apparent increase in the filling capacity of the tobacco treated with this method. The use of an atomized mixture formed by direct expansion of liquid carbon dioxide in step (a) of the process of the invention is therefore considered to be of critical importance for the subsequent steps of the process. The mechanism taking place is not known, but step (a) affects the structure of the tobacco and probably fixes it in an impressive way.

Suitably, in the method of the invention, the weight ratio in step (a) of expanding carbon dioxide and cooling tobacco is adjusted to an initial level by removing heat from the tobacco after reaching the desired temperature. The carbon dioxide snow present in the mist mixture forms gaseous carbon dioxide while
The ratio is selected such that the amount of residual carbon dioxide snow is consumed to such an extent that up to 40% by weight, preferably up to 10% by weight, relative to the weight of the tobacco, is consumed before the start of step (b). . Generally, the amount of carbon dioxide snow still present is inversely proportional to the initial tobacco temperature of step (b) in the process of the invention. For example, if the temperature of the tobacco is only about -30°C to -70°C, the amount of residual carbon dioxide snow is, for example, 40-10% by weight, so that the temperature of the tobacco is, for example, -70°C to -85°C. If so, the residual carbon dioxide snow will be only less than 10% by weight. In that case, it is preferred that no excess residual carbon dioxide snow is present. Thus, in a preferred embodiment, removing heat from the tobacco achieves a desired temperature for the tobacco, preferably from about -70°C to -100°C.
, especially after reaching -70°C to -85°C, the expanding liquid such that carbon dioxide snow is essentially no longer present, so that the entire amount of carbon dioxide snow initially present evaporates to gaseous carbon dioxide. Step (a) of the method of the invention is carried out by determining the weight ratio of carbon dioxide to the tobacco to be cooled. The equilibrium allows the process to be carried out optimally, allowing the tobacco filling capacity to be maximized and at the same time keeping the amount of carbon dioxide required, especially the amount of liquid carbon dioxide initially required, as low as possible. This makes it possible to carry out a particularly economical method of increasing Thus, troublesome additional formation of solid carbon dioxide and excessive conversion of solid carbon dioxide to liquid carbon dioxide during the subsequent step of treating the cooled tobacco with gaseous carbon dioxide does not occur. However, if the process is allowed to proceed and a certain deterioration of the expanded tobacco produced, after step (a) when the tobacco has reached the desired temperature, a small excess of solid dioxide which has not evaporated to gaseous carbon dioxide Carbon may still be present. however,
Generally, the best strategy for the process of the invention is to convert substantially all of the solid carbon dioxide to gaseous carbon dioxide.

Step (a) of the method of the invention (which is sensitive to the desired temperature for the tobacco) generally involves adjusting the weight ratio of liquid carbon dioxide to be expanded to tobacco to be cooled to the weight of the tobacco to be cooled. i.e. about 0.4 to 1.8, preferably about 0.7 per weight part of tobacco.
~1.1. In step (a) of the method of the invention, the preferred temperature for the tobacco is about -70°C to -8°C.
5°C, in particular about -78°C, such that either a small amount of excess carbon dioxide snow or no carbon dioxide snow is present.
The optimal amount of liquid carbon dioxide to expand. While simultaneously mixing the tobacco to be cooled, the expansion of liquid carbon dioxide from each pressure tank into the closed system is carried out at a pressure sufficient to form the required atomized mixture, i.e. generally less than about 6 bar. Absolute pressure, preferably about 0.2 to 1.0 bar (
(absolute pressure) to form a misty mixture of cold gaseous carbon dioxide, carbon dioxide snow, and optionally also liquid carbon dioxide required for cooling. Generally, preferred low temperatures can be reached in this way.

The expansion of liquid carbon dioxide into a closed system is carried out in a manner familiar to those skilled in the art. The expansion is generally effected by an expansion valve which provides a corresponding matching expansion to form the atomized mixture necessary for cooling the tobacco. Cold gaseous carbon dioxide, formed during the expansion of liquid carbon dioxide by suitable insulation,
It is ensured that perhaps all the cold air of the atomized mixture of carbon dioxide snow and optionally liquid carbon dioxide is used for cooling the tobacco, resulting in cooling by radiation of heat within each system and into the environment. There is no unnecessary consumption of agents. This is done by suitably insulating the system, ie in the first line of containers in which the tobacco is cooled. The inner lining of the container is most suitable as the insulation material. The internal insulating lining is of particular importance in vessels in which step (b) of the process of the invention is carried out, ie in which chilled tobacco is treated with gaseous carbon dioxide.

Preferably, before carrying out step (a) of the method of the invention, a large part of the air present is first removed in order to keep the pollution of the carbon dioxide which is subsequently recycled to the lowest possible level. Then, evacuate each system, eg, each mixing tank. At the same time, the method serves to remove air from the pores of the tobacco to be subsequently impregnated and to better prepare the pores for subsequent impregnation. Suitably, therefore, before carrying out step (a) of the process according to the invention, the system, for example a mixing tank in which this step is carried out, and also a double tank in which both step (a) and step (a) of the process according to the invention are carried out. The system is evacuated to a pressure of, for example, approximately 3 to 8 mbar, preferably 4 to 6 mbar. The tobacco treated in the process of the invention may be any tobacco material obtained from crushed or ground tobacco stems or tobacco ribs, such as so-called reconstituted tobacco. . However, preferably the method of the invention is carried out in processing tobacco leaves, especially cut tobacco. The moisture of the tobacco required as starting material in the process of the invention is not critical. Suitably the moisture content of the tobacco is between 10 and 25% by weight.

The period of time that the tobacco is contacted with the atomized mixture in step (a) is generally about 2 to 12 minutes, preferably about 4 to 8 minutes, before starting step (b). Most suitably, an atomized mixture of cold gaseous carbon dioxide, carbon dioxide snow and optionally also liquid carbon dioxide is connected to a mixing tank through the system, usually a mixing tank, in which the mixture is formed directly. supply to the pressure tank. To ensure optimal performance of step (b) of the method of the invention, the entire inner wall of the pressure tank is provided with insulation, most suitably with an insulating lining. Indeed, this procedure
that the gaseous carbon dioxide required in step (b) does not condense on the walls of the pressure tank, but substantially exclusively and selectively within the pores of the tobacco or exclusively on the porous surface of the tobacco; guaranteed. The problem of the formation of excess liquid carbon dioxide and the resultant so-called soaking of the tobacco without direct selective impregnation can be solved, in particular, by the additional measure of providing an insulating lining inside the pressure tank.
Almost controlled or completely avoided.

Suitably, steps (a), (b) and (c) of the process of the invention are carried out in an apparatus in which the mixing tank and the pressure tank are pressure-tight and vacuum-tight and are connected dual vessel systems. Suitably, horizontally extending, box-shaped or even tubular mixing tanks are used. One half of it is applied to a conveying means each containing the required amount of tobacco, and the other half is applied with its bottom side to a pressure tank. This pressure tank is provided with a lid that can be moved from inside the mixing tank, ie can be opened and closed firstly in a pressure-tight manner and then in a vacuum-tight manner. Preferably, the pressure tank is a cylindrical container with a bottom that can be closed firstly in a pressure-tight manner and also in a vacuum-tight manner. Gaseous carbon dioxide thus makes it possible to bring this pressure tank with a closed lid and bottom to the pressure necessary to carry out step (b) of the method of the invention. Of course, also preferably, the lid and the bottom, as well as the lining of the pressure tank, are provided with an internal insulating lining. For the reasons stated above, prior to the formation of the atomized mixture required for cooling and before mixing this mixture with tobacco, this closed dual tank system and the amount of tobacco contained therein and treated in the present invention. of,
Evacuate to about 3-8 mbar, preferably about 4-6 mbar. Here, naturally, the lid of the pressure tank opens toward the inside of the mixing tank, and the bottom of the pressure tank and the tobacco supply port are closed.

As mentioned above, half of the mixing tank, suitably arranged horizontally, is devoted to a conveying means containing the required amount of tobacco. Preferably, the conveying means is a trough placed below the tobacco supply opening, the bottom of which is formed by a conveyor belt, and is used in steps (b) and (c) of the method of the invention.
), a suitable device for directing the stored tobacco contained in the tub approximately corresponding to the amount of tobacco to be processed in the pressure tank directly into the opening in the lid of the pressure tank is placed in this tank, facing the center of the mixing tank. The front and sides of the bucket are included. The transport pipe for the introduction of liquid carbon dioxide and the expansion valve at the end of the transport pipe are therefore preferably arranged in the wall of the mixing tank in such a way that the expansion valve extends directly towards the opening of the pressure tank. In this way, the atomized mixture of cold gaseous carbon dioxide, solid carbon dioxide snow and optionally also some liquid carbon dioxide formed during the expansion of the liquid carbon dioxide is supplied by the conveying means immediately after its formation. The mixture is mixed with the appropriate amount of smoked tobacco and fed into the pressure tank in the already mixed state.

The evacuation of the dual tank system for carrying out steps (a), (b) and (c), which optionally precedes step (a) of the process of the invention, can be carried out for example by means of a vacuum pump via a duct. This may be done in any suitable manner, such as through a valve located in a pressure tank, connected to a pressure tank. A corresponding valve may also possibly be placed on the mixing tank. To carry out step (b) of the method of the invention, the desired temperature is selected, i.e. from about -30°C to -100°C, preferably about -7°C.
The tobacco, cooled to 0°C to -85°C, is placed in the closed pressure tank at a pressure of about 15 to 35 bar, preferably about 25 to 30 bar.
Gaseous carbon dioxide from a pressure vessel is added until a pressure of about 26-28 bar is reached. In this case, only the tobacco pores are further treated under selective liquefaction of liquid carbon dioxide. Therefore, when feeding into a pressure tank, the temperature of the gaseous carbon dioxide used is suitably between about -25°C and +15°C.
°C, preferably from about -20°C to +10°C, especially from about +4°C
+6°C and the contact time with gaseous carbon dioxide in the pressure tank is for example about 2 to 12 minutes, preferably about 4 to 8 minutes.
minutes, especially 6 minutes. Thus, in step (b), selective impregnation with liquid carbon dioxide substantially only increases the weight of the tobacco pores by about 10-40% by weight relative to the initial untreated tobacco. After this treatment, the temperature of the impregnated tobacco is about -25 to -45°C. The filling of the pressure tank with gaseous carbon dioxide takes place by means of a plug valve arranged on the pressure tank, which plug valve is connected to a supply container for gaseous carbon dioxide through a corresponding duct. Suitably the valve has its duct arranged at the bottom of the pressure tank.

After impregnating the tobacco with liquid carbon dioxide and before carrying out step (c) of the process of the invention, in order to convert the liquid carbon dioxide contained in the pores of the tobacco into solid carbon dioxide, The carbon dioxide pressure in the pressure tank is expanded from the previous condensation pressure to a substantially lower pressure as rapidly as possible, suitably first reduced to approximately atmospheric pressure. This expansion may be effected by the same plug and the same duct used for supplying gaseous carbon dioxide in step (b) above. After expansion of the pressure in the pressure tank, by slowly applying a vacuum, the residual carbon dioxide still contained is recovered and reused later. As mentioned above, the expansion causes the conversion of the liquid carbon dioxide initially contained in the pores of the tobacco to solid carbon dioxide, while simultaneously converting a portion of the initial carbon dioxide to gaseous carbon dioxide. The ratio of solid carbon dioxide and gaseous carbon dioxide obtained by this method naturally depends on the respective process conditions. Generally, the weight ratio is about 0.2 to 1.0/1, preferably about 0.3 to 0.6/1. Thus, after step (c) of the method of the invention, the pores of the treated tobacco will generally be from about 2 to about 1 pores based on the weight of the initial untreated tobacco.
Contains solid carbon dioxide in an amount of 7%, preferably about 8 to about 15%. Possibly for economic reasons and optimum utilization of the required carbon dioxide, the capacity of the pressure tank in which steps (b) and (c) of the process of the invention are carried out is adapted to the amount of chilled tobacco to be processed therein. . As a result, typically at least two-thirds of the pressure tank is filled with chilled tobacco. Depending on the process conditions and desired effect, it may be desirable to select a higher or lower filling rate.

After step (c) of the process of the invention, the tobacco with the pores filled with solid carbon dioxide is removed by opening the bottom of the pressure tank and then, if desired, likewise insulated and heated as necessary. The tobacco is then introduced through a cooled supply container into a conventional apparatus in which it is treated with hot gas to obtain the desired expansion. This is step (d) of the method of the invention. The methods applied in this step (d) are known to the person skilled in the art and include, for example, tobacco containing solid carbon dioxide and a hot gas, preferably air, steam or a mixture thereof, usually at a temperature of about 150°C to 350°C, preferably generally includes processing at a temperature of about 200°C to 300°C, the processing time being as long as necessary for the expansion, and as appropriate for each selected temperature, to avoid undesired damage to the tobacco. Keep the time as short as possible. After emptying the pressure tank, the bottom is closed again and the connected dual tank system is returned to its normal position. As a result, after inserting each amount of tobacco into the conveying means of the mixing tank, each filled tobacco is
Subjected to steps (a) to (c) of the method of the present invention.

Since a larger amount of gaseous carbon dioxide is produced from the liquid carbon dioxide during the formation of the atomized cold mixture, a certain amount of It is appropriate to remove this excess gaseous carbon dioxide under conditions. The carbon dioxide thus obtained, as well as the carbon dioxide present in step (c) and additionally formed from liquid carbon dioxide, can be converted into carbon dioxide by a suitable method, for example by condensation, cooling and reconstitution. Collect in carbon supply container. This allows the extensive circulation of carbon dioxide necessary for the process of the invention, which contributes to a further increase in the profitability of the process. Only the amount of carbon dioxide present in solid state in the tobacco after step (c) of the process of the invention is lost. Only in step (d) is this carbon dioxide converted into gaseous carbon dioxide and simultaneously mixed with the hot gas required for heat treatment in order to obtain expansion of the tobacco. Separation of gaseous carbon dioxide present in the gas mixture is also often possible, but such separation is generally not profitable. Therefore, the separation is usually abandoned. As far as steps (a) to (c) are concerned, the method according to the invention may be carried out in the apparatus shown in the accompanying drawings and partly in cross section. Conventional equipment for the expansion of tobacco by treatment with hot gases may be used to carry out step (d) of the process of the invention.

FIG. 1 shows in detail a dual tank system consisting of a horizontally arranged cylindrical mixing tank 1 and a connected vertically arranged cylindrical pressure tank 2. Mixing tank 1
The right end portion of is applied to the conveying means 3 which accommodates the cigarettes 4. The conveying means 3 consists of bins 5 suitable for accommodating each quantity of tobacco, with a conveyor belt 8 on the bottom and a proportioning roller on the front.
(ortioningrollers) 7. Through the feed opening 9, which includes the stopper 8, the quantity of tobacco to be treated is fed into the bin 5 of the conveying means 3. The pressure tank 2 has a flange on its head to the left bottom of the mixing tank 1, and the pressure tank 2 consists of a lid 10 and a bottom 11, both of which are in the closed position shown in dotted lines. The lid and the bottom 11 in the open position can be operated independently of each other for opening and/or closing. At the bottom of the pressure tank 2, a gaseous carbon dioxide supply container (
A plug valve 12 is provided which is connected to a valve (not shown in the figure). This duct 13 is connected to the pressure tank 2 to bring it to the pressure necessary for carrying out step (b) of the method according to the invention by supplying gaseous carbon dioxide, and to bring the pressure tank 2 to the pressure necessary for carrying out step (c) of the method according to the invention.
) and later evacuate the pressure tank 2 for removal of residual carbon dioxide. The wall of the pressure tank 2 contains a plug valve 15 which is connected via an exhaust duct 14 to a vacuum pump (not shown in the figure) and which allows the steps of the method of the invention (
Prior to a), the dual tank system is evacuated to remove problematic air present both within the dual tank system and in the tobacco pores. The interior of the pressure tank 2, ie the inner shell, the lid 10 and the bottom 11, is covered with a heat insulating lining 16. At the top of the left side of the mixing tank 1 is arranged an expansion valve 17 which supplies liquid carbon dioxide from a supply container (not shown in the figure) through a duct 18. The opening of the expansion valve 17 forms an atomized mixture 19 of cold gaseous carbon dioxide, carbon dioxide snow and some liquid carbon dioxide, which is dispensed directly into the upper opening of the pressure tank 2 and the tobacco 4
This is mixed with the mixture at the same time as it is supplied.

[0018]

[Example] The steps of the method of the present invention (
Carrying out steps a) to (c) will be described in detail in the Examples below. Example 1 Step (a) Humidity of about 21% and ambient temperature (about 18-2
10 kg of cut Virginia tobacco (2°C) 4
into the bottle 5 of the conveying means 3 of the mixing tank 1, which has a tank capacity of about 300 liters, by opening the stopper 8 and inserting it into the supply port 9.
Fill through. Immediately thereafter, the plug 8 of the mixing tank is closed. The lid 10 is opened and the bottom 11 is closed, and from a dual tank system consisting of a mixing tank 1 and a pressure tank 2 with a tank capacity of about 150 liters (total tank capacity is about 450 liters),
Via the plug valve 15 into the exhaust duct 14 located in the pressure tank 2, substantially all the air is removed using a vacuum device, i.e. until the absolute pressure in the dual tank system reaches approximately 4 mbar. Exhaust. As a result, the air contained in the pores of the tobacco 4 is also substantially completely removed. Immediately thereafter, the plug valve 15 is closed. Next, expansion valve 1
7 is opened and about 8 kg of liquid carbon dioxide is fed through duct 18 within about 6 minutes, converting it into a misty cold mixture of cold gaseous carbon dioxide, carbon dioxide snow and some liquid carbon dioxide. Again within 6 minutes, a total of 10 kg of tobacco contained in the bottle 5 is uniformly blended into the pressure tank 2, and at the same time, it is mixed with the atomized gas formed by the expansion valve 17 and uniformly cooled. When the expansion valve is opened,
Conveyor belt 6 and connected proportioning
Activate roller 7. Duct 1 connected to supply container
In 8, the liquid carbon dioxide has an absolute pressure of about 14 bar and a temperature of about -35°C. During the supply of the cold atomized mixture through the expansion valve 17 and the mixing of this mixture with the tobacco 4, an initial pressure of about 4 mbar in the dual tank system is increased to an absolute pressure of about 5 bar. Immediately thereafter, the pressure is gradually reduced to approximately 0.6 bar absolute by opening the plug valve 12 and venting through the duct 13. At the end of approximately 6 minutes of processing time,
The tobacco 4 is cooled to a temperature of approximately -80° C., but at this moment the pressure in the mixing tank 1 and the pressure tank 2 of the dual tank system is increased to a further approximately 0.25 bar by means of a vacuum pump connected to the duct 13. reduced to absolute pressure, so that the temperature of the tobacco 4 becomes even more uniform, and at the same time additional gaseous carbon dioxide is recovered. Duct 13
The gaseous carbon dioxide removed through the system is recovered and reused. For example, it can be easily brought to higher pressures and converted to liquid carbon dioxide by further compression. The carbon dioxide thus obtained can therefore be completely reused and recycled.

Step (b) When the desired temperature of -80° C. is reached, the lid 10 of the pressure tank 2 is closed. Immediately thereafter, from about -15°C of the initial temperature to about +15°C of the final temperature.
Gaseous carbon dioxide in the range . As a result, the absolute pressure in the pressure tank 2 is approximately 26 bar, which allows the tobacco 4 in the pressure tank 2 to be treated for approximately 6 minutes, with the liquid carbon dioxide under condensation of the gaseous carbon dioxide. Selectively impregnates the pores. This impregnation increases the weight of the tobacco by about 28% compared to the original untreated tobacco 4.

Step (c) The pressure in the pressure tank 2 is first rapidly expanded via the duct 13 to an absolute pressure of 1 bar, and then again via the duct 13 to an absolute pressure of 0.
It is evacuated to 2 bar, thereby recovering all the carbon dioxide present in the pressure tank 2. This expansion, which lasts for approximately 2 minutes, substantially converts a portion (approximately 1/3) of the liquid carbon dioxide contained in the pores of the tobacco 4 into solid carbon dioxide, while the other portion (approximately 3 2/2) is evaporated to gaseous carbon dioxide. After said expansion and said evacuation, the bottom 11 of the pressure tank 2 is opened and the tobacco containing solid carbon dioxide in the pores is removed. Like the original filling, the tobacco thus obtained is a flexible raw material with unfrozen fibers. Therefore, no mechanical processing is required to break it into a flexible raw material bulk.

Step (d) Approximately 25
Tobacco 4 containing solid carbon dioxide is expanded with a mixture of air and steam at a temperature of 0°C. As a result, the filling volume is approximately 11.4 cm3/g (the initial filling volume is 5.5 cm3/g).
5cm3/g) is obtained. These data were confirmed by Borgwaldt's fill capacity test using tobacco with a moisture content of 12.6%. The length of the resulting tobacco fibers is substantially unchanged from the initial tobacco. The tobacco yield is 99.7% by weight based on the initial tobacco weight. This shows that the method of the invention is substantially free of tobacco losses caused by, for example, friction, any other comminution, or any other effects. The aroma of the treated tobacco is substantially unchanged from its initial aroma.

Examples 2 to 7 As in Example 1, furthermore, the initial humidity was 2
A sample of 1% Virginia tobacco is processed in the same dual tank system. The process conditions may be different from those in Example 1 and the test results obtained are shown in the table below.
Table Implementation number
2 3 4
5 6 7─
──────────────────────────
────────── Tobacco amount (kg)
10 10 10
10 10 10 Process (a
Consumption of liquid carbon dioxide in ) 4 5.
3 6.7 7.5 8.4
7.55 Cooling temperature (℃) in step (a) -31
-52 -63 -79
-90 -78 Absolute pressure (bar) of gaseous carbon dioxide in step (b) 26
26 26 26 2
6 30 Amount of solid carbon dioxide (%) contained in the tobacco pores at the end of step (c) 2.5 3.7
8.2 12 15
12.8 Filling capacity (cm3/g) 8.5
9.35 10 10.67
10.83 11.04 Humidity (%)
(12.6) (12.5)
(12.1) (12.63) (12.8)
(12.53) The other properties of the tobacco obtained in Examples 2-7 above are the same as the additional properties in Example 1 above.

[0023]

Effects of the invention: It is extremely economical due to its low carbon dioxide requirement and consumption and its reusability, and it can substantially increase the filling capacity by selectively impregnating only the small pores and porous surfaces of the tobacco. To provide a new method for expanding tobacco.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a dual tank system used in the present invention.

[Explanation of symbols]

1 Mixing tank 2 Pressure tank 3. Transportation means 4. Cigarettes 10 Lid 11 Bottom 16 Insulation lining 19 Atomized mixture

Claims (19)

[Claims] Claim 1: (a) cooling tobacco and cold carbon dioxide to a predetermined temperature by mixing them in a predetermined weight ratio; (b) cooling the same to a predetermined pressure by gaseous carbon dioxide; , impregnating the cooled tobacco with liquid carbon dioxide by treatment for a predetermined contact time under condensation of the gaseous carbon dioxide;
(c) converting the liquid carbon dioxide that condenses in the tobacco into solid carbon dioxide and at the same time forming gaseous carbon dioxide by rapidly reducing the pressure of the carbon dioxide; (d)
Expansion of tobacco containing solid carbon dioxide is carried out by subjecting it to a hot gas treatment, step (a) involves direct expansion of liquid carbon dioxide from a pressure vessel into a closed system to produce cold gaseous dioxide. The tobacco is heated at about -30°C to -100°C, preferably at about -70°C, while forming a mist-like mixture of carbon, carbon dioxide snow, and optionally liquid carbon dioxide, and simultaneously adding the tobacco. A method of expanding tobacco characterized by cooling to a temperature of ~-85°C. 2. The carbon dioxide snow initially present in the atomized mixture is removed by removing heat from the tobacco after the weight ratio of expanding liquid carbon dioxide and cooling tobacco reaches a desired temperature. is consumed to such an extent that the amount of residual carbon dioxide snow is up to 40% by weight, preferably up to 10% by weight, relative to the weight of the cooled tobacco before the start of step (b), while forming gaseous carbon dioxide. A method according to claim 1, characterized in that the ratio is such that: 3. By removing heat from the tobacco after the weight ratio of expanding liquid carbon dioxide to cooling tobacco reaches a desired temperature, substantially all of the carbon dioxide snow is evaporated to gaseous carbon dioxide snow. 3. A method according to claim 1 or 2, characterized in that the method is selected to cause 4. The weight ratio of the liquid carbon dioxide to be expanded to the tobacco to be cooled is about 0.4 to 1.8, preferably about 0.7 to 1.0, relative to the weight of the tobacco to be cooled. A method according to any one of the preceding claims, characterized in that: 5. Process according to claim 1, characterized in that the liquid carbon dioxide is expanded to an absolute pressure of less than about 6 bar, preferably between 0.2 and 1.0 bar. 6. Process according to claim 1, characterized in that the mixture of atomized mixture and tobacco is fed directly through a mixing tank into a pressure tank connected to said mixing tank. 7. A method as claimed in claim 1, characterized in that step (b) is carried out in a pressure tank, the interior of said pressure tank being provided with an insulating lining. 8. A method according to any one of the preceding claims, wherein the mixing tank and the pressure tank are an interconnected pressure-tight and vacuum-tight dual tank system. 9. The method according to claim 8, characterized in that, before forming the atomized mixture and mixing it with the tobacco, the closed dual tank system containing the amount of tobacco to be treated is evacuated. the method of. 10. Said multiple tank system comprises about 3 to 8
10. Process according to claim 9, characterized in that it is evacuated to a pressure of about 4 to 6 mbar. 11. The mixing tank comprises a conveying means for containing the required amount of tobacco, and the conveying means unitizes the tobacco according to the amount of liquid carbon dioxide consumed and the amount of atomized mixture formed. , into the pressure tank. 12. A method as claimed in claim 1, characterized in that the pressure tank has a lid and a bottom, both of which are pressure-tight and vacuum-tight. 13. In step (b), about 15 to 35
characterized in that the cooled tobacco is treated with gaseous carbon dioxide in a tank at a pressure of about 25 to 30 bar, with selective condensation of liquid carbon dioxide substantially only in the pores of the tobacco. A method according to any one of the preceding claims. 14. When fed into a pressure reactor, the gaseous carbon dioxide is at a temperature of about -25°C to +15°C, preferably about -5°C.
Claim 13 characterized in that the temperature is from °C to +10 °C.
Method described. 15. The contact time with gaseous carbon dioxide is about 2.
A method according to any one of the preceding claims, characterized in that the duration is ~10 minutes, preferably about 4 to 8 minutes. 16. Impregnation with liquid carbon dioxide in step (b) reduces the weight of the tobacco to about 10 to 4
A method according to any one of the preceding claims, characterized in that the increase is 0%. 17. Step (c) is characterized in that the pressure of the carbon dioxide is reduced as rapidly as possible to approximately atmospheric pressure to convert the liquid carbon dioxide in the pores of the tobacco into solid carbon dioxide. A method according to any one of the preceding claims. 18. The carbon dioxide present in the pressure tank and the gaseous carbon dioxide additionally formed by expansion of the liquid carbon dioxide contained in the pores of the tobacco are recovered and reused by means of a mild vacuum. Claim 17
Method described. 19. In step (d), the temperature of about 150°C to
at a temperature of 350°C, preferably about 200°C to 300°C,
A method according to any one of the preceding claims, characterized in that the tobacco containing solid carbon dioxide is subjected to an expansion treatment.